1var mysql = require('mysql');
2
3// connect to the db
4dbConnectionInfo = {
5  host: "localhost",
6  port: "3306",
7  user: "root",
8  password: "root",
9  connectionLimit: 5, //mysql connection pool length
10  database: "db_name"
11};
12
13//For mysql single connection
14/* var dbconnection = mysql.createConnection(
15        dbConnectionInfo
16); 
17
18 dbconnection.connect(function (err) {
19    if (!err) {
20        console.log("Database is connected ... nn");
21    } else {
22        console.log("Error connecting database ... nn");
23    }
24}); 
25
26*/
27
28//create mysql connection pool
29var dbconnection = mysql.createPool(
30  dbConnectionInfo
31);
32
33// Attempt to catch disconnects 
34dbconnection.on('connection', function (connection) {
35  console.log('DB Connection established');
36
37  connection.on('error', function (err) {
38    console.error(new Date(), 'MySQL error', err.code);
39  });
40  connection.on('close', function (err) {
41    console.error(new Date(), 'MySQL close', err);
42  });
43
44});
45
46
47module.exports = dbconnection;
48

1var pool  = mysql.createPool({
2      connectionLimit : 10,
3      host            : 'example.org',
4      user            : 'bobby',
5      password        : 'pass'
6    });
7    
8pool.getConnection(function(err, connection){
9    if(err){
10        return cb(err);
11    }
12    connection.changeUser({database : "firm1"});
13    connection.query("SELECT * from history", function(err, data){
14        connection.release();
15        cb(err, data);
16    });
17});
18